.container{
  border: 1px solid red;
  padding: 0 150px 0 150px;
  min-width: 500px;
}
.container::after{
  content: "";
  display: block;
  clear: both;
}
.box{
  /*min-width: 500px;*/
  min-height: 200px;
  float: left;
}
.main{
  width: 100%;
  background: #0f0;
}
.left{
  width: 150px;
  background: #f00;
  margin-left: -100%;
  position: relative;
  left: -150px;
}
.right{
  width: 150px;
  background: #00f;
  margin-left: -150px;
  position: relative;
  left: 150px;
}
